Optical functionality sheet, and planar light source and image display apparatus using the same sheet

ABSTRACT

An optical functionality sheet provided with microlenses and a functional film (reflective film or light-blocking film/light-diffusing layer), with the above described functional film formed upon a patterned transparent conductive film. Thereby, self-alignment exposure using microlenses is made possible, and an optical functionality sheet with good directivity with respect to incident light, and good angle of visibility characteristics, can be realized.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an optical sheet that has afunction of improving a directivity of light rays—that is, an opticalfunctionality sheet composed of a microlens array and a reflective filmor light-blocking film—and a planar light source, and liquid crystaldisplay apparatus using this sheet.

[0002] Recently, image display apparatuses, of which liquid crystaldisplay panels are representative examples, have come into wide generaluse as display means for personal computers, workstations, and so forth.In terms of the quality of the images displayed using such displayapparatuses, the characteristics demanded are high brightness and highdisplay contrast, together with a wide angle of visibility.

[0003] In order to realize the above described image quality, aninstallation of a light-diffusing plate between a liquid crystal displaypanel and a back light source has been disclosed in JP-A-6-95099specification. Also, a method has been disclosed for enlarging an angleof visibility by installing a sheet that has a microlens array and alight-blocking layer on a liquid crystal image display surface.

[0004] Moreover, in JP-A-10-39769 specification, a screen thatcoordinates array patterns of microlenses and light-blocking film hasbeen disclosed as the screen of a rear-projection type projectionapparatus.

[0005] When the above described wide-angle-of-visibility sheet is usedin a liquid crystal display apparatus, characteristics required of thelight source are high directivity and nearly collimated light rays(parallel light rays). The reason for this is that, if the light rayswere not parallel, the rays would not be converged sufficiently by themicrolenses, and would be projected onto areas where the light should beblocked. This would cause light loss and reduce the brightness of theimage display apparatus.

[0006] General planar light sources (backlights) for the above describeduse employ various kinds of diffusion plates that diffuse light beamsrandomly, in order to achieve uniformity of brightness of the lightemitting surface, and the beams emitted from this light emitting surfacedo not have directivity.

[0007] Furthermore, a so-called louver sheet, comprising many rows oflight-blocking walls aligned with the direction of travel of the beams,is known as a light source that has directivity. By means of a louversheet, it is possible to obtain a planar light source that has arbitrarydirectivity, by taking emitted light with a spread of 120 degrees ormore in an emitting surface, for example, and cutting off beamstraveling in other than the required direction by means oflight-blocking walls. However, this sheet has low light usageefficiency, and is not suitable for the image display apparatus which isan objective of the present invention.

[0008] As another method, a method has been disclosed whereby a prismsheet arrayed with a large number of minute triangular prisms is placedon the surface of a photoconductive plate. This is achieved bycontrolling to some extent the direction of emission of the beams. Thisprism sheet enables directivity of the order of ±30 degrees to beobtained, but does not meet the requirements of the image displayapparatus which is an objective of the present invention.

[0009] A light ray directivity sheet that eliminates the above describedproblems, has high light directivity and light usage efficiency, ismoreover of thin shape, and enables a uniform planar light source to beobtained, and a directional planar light source using this, have beendisclosed in JP-A-9-1675133 specification and JP-A-10-241434specification.

[0010] This method consists of a light ray directivity sheet, onesurface of which comprises a group of microlenses in which unit lensesare arrayed, and on the other surface of which a light ray blocking film(reflective film) is formed, wherein, at least, areas in the vicinity ofthe focal points of light rays entering from the microlens group side ofthe above described light ray blocking film are made apertures. Bypositioning the surface of this light ray directivity sheet on which thelight ray blocking film is formed on the light source side, andpositioning the microlens surface on the viewing side (liquid crystaldisplay element side), a planar light source is obtained that is givendirectivity by the operation of the microlenses.

SUMMARY OF THE INVENTION

[0011] By using a planar light source fitted with the above describedlight ray directivity sheet using microlenses, and an angle ofvisibility enlargement sheet using similar microlenses, it is possibleto realize an image display apparatus with high brightness and a widefield of view.

[0012] However, with any sheet, there are many problems that need to besolved in the actual construction process.

[0013] First of all, there are major limitations in the construction ofan angle of visibility enlargement sheet. That is to say, when amicrolens array and a light-blocking layer (black matrix) forsuppressing the re-reflection of external light reflected by the surfaceof this microlens array are combined, it is essential for the layoutpatterns of the microlenses and light-blocking layer to be preciselypositioned relative to each other, since a slight misalignment willhalve their function.

[0014] Known common methods for forming a light-blocking layer includeforming as a thin metal film, and a method whereby a photosensitiveresin film, in which a pigment such as carbon black has been dispersedor in which a black or other dye has been dissolved, is formed on asubstrate, and is patterned by means of photolithography

[0015] However, if the light-blocking layer and the microlenses areformed by totally independent processes, and the two are combined later,it can be said that it is difficult to align the two accurately withinseveral μm. When the size of the microlenses is very small (several tensof μm), in particular, accurate alignment is extremely difficult.

[0016] On the other hand, as a solution to the problems relating to anangle of visibility enlargement sheet, sensitization of a photosensitivelayer by energy ray irradiation via optical elements (for example, amicrolens array) corresponding to a black matrix pattern, and forming ablack matrix of the desired pattern, has been disclosed inJP-A-10-246804 specification.

[0017] As the microlenses and the transparent parts of thelight-blocking layer are formed by means of self-alignment, an advantageof this method is that it is easy to coordinate the respective patternpositions precisely, but the following problem arises in realizing this.

[0018] Namely, with the above described method, from the viewpoint ofthe work processes, a positive-type resist is generally used whereby theparts irradiated with energy rays are sensitized and become soluble in asolvent. However, in order for the light-blocking layer to be formedsimultaneously by this method, the use of a non-transparent materialcontaining carbon black, or a black dye or pigment, etc., in the abovedescribed resist is assumed. Therefore, the transmittivity of the energyrays, and especially the light rays used for pattern forming, isdecreased, and it is difficult to obtain a prescribed pattern.

[0019] Therefore, the problem arises of it being necessary to spend along time on energy ray irradiation, or to make the resist film thin, inorder to compensate for the fact that the photo-transmittivity is low.Thus, the exposure process is time-consuming, and it is difficult toobtain a light-blocking film with a high optical density (highlight-blocking capability).

[0020] Another method is one in which, after a layer constituting thelight-blocking layer has been formed using a negative-type resist, thelight-blocking layer is patterned by means of photolithography. However,the problem with this method is that the work processes are even morecomplex, making it impractical.

[0021] On the other hand, the same kind of problems as described abovealso arise with regard to a light ray directivity sheet usingmicrolenses. That is to say, the array patterns of the microlenses andthe light-blocking layer must be accurately aligned in order for thefunction to be fully implemented. This is because any misalignmentreduces the parallelism (collimation) of the emitted beams, with aresulting problem of lower emission efficiency of the planar lightsource.

[0022] A reflective film, such as a metal film or titanium oxide, hasbeen proposed as the light-blocking film of the above described lightray directivity sheet, and a self-alignment method, using lenses, hasbeen proposed as the manufacturing method, as in the case of an angle ofvisibility enlargement sheet.

[0023] That is, a negative-type photo-resist is applied to the oppositesurface from that with the group of microlenses, and the resist isexposed and developed by irradiation with parallel ultraviolet lightfrom the lens formation surface side. By this means, a band-shapedpattern is formed on the parts corresponding to the lens focal points.

[0024] Next, a film that constitutes the light-blocking film is formedupon this. To be specific, a coating material in which titanium oxide isdispersed in acrylic resin is applied, or a film of metal, such asaluminum, is applied by vapor deposition, or a coating material in whichcarbon black is dispersed in acrylic resin is applied. Then, part of thearea of the resist on which the band-shaped pattern has been formed (theprojecting area) is cut away. The band-shaped pattern is completelyremoved with resist remover.

[0025] The above described method is called the lift-off method. Thismethod makes it possible to obtain a light ray directivity sheet onwhich areas in the vicinity of the microlens focal point are madeapertures, but it involves many processes, and also presents thefollowing problems.

[0026] Namely, it is necessary to make the resist film thick—a problemcharacteristic of lift-off—and it is difficult to obtain ahigh-precision pattern with a photolithographic process. Also, anexcessive load is applied to the resist in the process for forming thelight-blocking film, and complete lift-off of the resist is difficult,among other things.

[0027] In order to solve the above described problems, and to obtainfunctionality sheets with excellent optical characteristics—that is, alight ray directivity sheet and wide-angle-of-visibility sheet—thepresent invention employs a method whereby a patterned transparentconductive film is used, and a light-blocking film or reflective film isformed thereupon.

[0028] That is to say, in the present invention, a transparentconductive film is formed on the other side of a transparent member onwhich microlenses are formed. Next, a positive-type photo-resist film isformed on this transparent conductive film, and then so-calledself-alignment exposure is carried out, whereby exposure is performedfrom the side on which the microlenses are formed, and aperture areas(transparent portions) are formed on the transparent conductive film byremoving the resist, by development, from the lens convergence areas.After this, the transparent conductive film at the aperture areas isremoved using an etching method. Lastly, with the transparent conductivefilm as an electrode, a light-blocking film is formed on thistransparent conductive film using a method such as electrodepositioncoating, metal plating, electrolysis, or electroforming.

[0029] Patterning can be performed easily and with high precision usingmeans whereby patterning is performed by means of light irradiation ofthe photo-resist film from the side on which the microlenses areformed—that is, self-alignment exposure means—via the above describedtransparent conductive film. Also, as electrical means such aselectrodeposition is used for formation of the light-blocking film, withtransparent film as an electrode, it is possible to form a colored filmwith low transparency, such as a black light-blocking film, a whitediffuse reflection film, or a metal film, on a prescribed area with highprecision, and to a degree of thickness as necessary.

[0030] Therefore, according to the present invention, it is possible tomanufacture, with high productivity, an optical functionality sheetprovided with microlenses and a diffusive white reflecting film or alight-blocking film, and also a directional planar light source andliquid crystal display apparatus using these.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] These and other features, objects and advantages of the presentinvention will become more apparent from the following description whentaken in conjunction with the accompanying drawings wherein:

[0032]FIG. 1 is an explanatory drawing showing the construction andmanufacturing process of an optical functionality sheet (lightdirectivity characteristics) that constitutes a first embodiment;

[0033]FIG. 2 is an explanatory drawing showing the construction andmanufacturing process of an optical functionality sheet (lightdirectivity characteristics) that constitutes a second embodiment;

[0034]FIG. 3 is an explanatory drawing showing the construction andmanufacturing process of an optical functionality sheet (lightdirectivity characteristics) that constitutes a third embodiment;

[0035] FIGS. 4A-4E are explanatory drawings showing the construction andmanufacturing process of an optical functionality sheet (lightdirectivity characteristics) that constitutes a fourth embodiment;

[0036]FIG. 5 is an explanatory drawing showing the construction andmanufacturing process of an optical functionality sheet (angle ofvisibility enlargement characteristics) that constitutes a fifthembodiment;

[0037]FIG. 6 is an explanatory drawing showing the construction andmanufacturing process of an optical functionality sheet (angle ofvisibility enlargement characteristics) that constitutes a sixthembodiment;

[0038]FIG. 7 is an explanatory drawing showing the construction andmanufacturing process of an optical functionality sheet (angle ofvisibility enlargement characteristics) that constitutes a seventhembodiment;

[0039]FIG. 8 is an explanatory drawing showing the construction andmanufacturing process of an optical functionality sheet (angle ofvisibility enlargement characteristics) that constitutes an eighthembodiment;

[0040]FIG. 9 is an explanatory drawing showing an embodiment of a planarlight source using an optical functionality sheet;

[0041]FIG. 10 is an explanatory drawing showing an embodiment of angleof visibility enlargement characteristics using an optical functionalitysheet.

[0042]FIG. 11 is an explanatory drawing showing an embodiment of aliquid crystal display apparatus; and

[0043]FIGS. 12A and 12B are explanatory drawings showing anotherembodiment of a liquid crystal display apparatus.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0044] Embodiments of the optical functionality sheet that constitutesthe present invention, and cases applying to a planar light source andliquid crystal display apparatus (abbreviated to LCD (Liquid CrystalDisplay) below) using this, will be described below in detail asexamples by using the accompanying drawings.

[0045] The optical functionality sheet in the embodiments describedbelow denotes a compound sheet of any of various kinds of plastic filmapproximately 0.01 to 5 mm in thickness, that sheet and its substrate, aglass sheet and its substrate, an organic substance and inorganicsubstance.

[0046]FIG. 1 shows the configuration and manufacturing process of anoptical functionality sheet that constitutes a first embodiment of thepresent invention.

[0047] (1) Microlens Forming

[0048] Ultraviolet-setting resin is injected between the lens grooves ofan approximately 300 μm thick Ni stamper (not shown) and a transparentsheet 1 a, and is hardened by irradiation with ultraviolet light, toform microlenses 2.

[0049] There are no particular restrictions as to the material of thetransparent sheet 1 a, as long as it is, at least, a substance that istransparent to visible light, and while glass, various kinds of plasticmaterials, and so forth, can be considered, use of a plastic material isdesirable from the viewpoint of workability.

[0050] To be specific, desirable plastic materials are polyester resin,acrylic resin, urethane resin, epoxy resin, polycarbonate resin,polystyrene resin, TAC (triacetyl cellulose), PET (polyethyleneterephthalate), PEN (polyethylene naphthalate), and compounds of these,but are not limited to these.

[0051] Also, possible methods for forming the microlenses 2 includemanufacturing methods that reproduce a shape using a die or stamper,photolithography and manufacturing methods using it, and so forth, butfrom the viewpoint of productivity, etc., an above describedmanufacturing method using a die or stamper is the most desirable.

[0052] To be specific, desirable methods for microlens forming includedirect lens forming methods by means of thermal pressing, extrusionforming, rolling forming, vacuum forming, and so forth, using the abovedescribed optical functionality sheet 1 a—that is, methods whereby themicrolenses 2 and the optical functionality sheet 1 a become an integralentity, and methods whereby ultraviolet-setting resin, thermosettingresin, thermoplastic resin, etc., is selected as appropriate and formedon the optical functionality member 1 a, and the shape is reproducedusing a die or stamper. Of the latter methods, a method using an acrylicultraviolet-setting resin, which offers quick setting and is also simplein terms of equipment, is desirable.

[0053] (2) Forming of Transparent Conductive Film

[0054] Next, a transparent conductive film 3 is formed on the oppositeside of the transparent sheet 1 a from that on which the above describedmicrolenses 2 are formed. ITO (indium tin oxide), tin oxide, Nesa(SnO₂), Nesatron (In₂O₃), etc., can be used for the transparentconductive film, but of these ITO is the most suitable, and an ITO filmcan be formed using well-known sputtering or vacuum vapor depositionmethods.

[0055] In order to improve the adherence to the transparent sheet 1 a atthis time, it is desirable to first apply a thin silica film coating,then form the ITO or other transparent conductive film upon this.

[0056] (3) Patterning of Transparent Conductive Film

[0057] A photo-resist 27 is applied upon the above described transparentconductive film. As the photoresist material, a resist of which areasexposed to light dissolve in resist remover—that is, a positive-typeresist—is used. Next, parallel ultraviolet (UV) light rays 28 areprojected from the microlenses 2 side, exposing only areas of thephotoresist film 27 where parallel light rays are converged by themicrolenses 2—that is, only areas in the vicinity of the central axes ofthe microlenses 2. This is called self-alignment exposure. Followingthis, the photo-resist film 27 is developed by immersing the transparentsheet 1 a in developer. By this means, a resist pattern 27 a is obtainedwith the resist film 27 in the vicinity of the central axes of themicrolenses 2 removed. Post-baking is performed as necessary.

[0058] Next, the transparent conductive film 3 is etched. Both dryetching and wet etching are well known as etching methods, but from aproductivity viewpoint, use of wet etching is desirable.

[0059] In this embodiment, etching of the transparent conductive film 3is performed by using an HBr water solution, or an FeCl₃ (1N),hydrochloric acid (1N), nitric acid (1N), cerium nitrate (0.1N) mixedwater solution, and a transparent conductive film 3 with the prescribedpattern is formed. Following this, unwanted resist film 27 is removed byusing a strongly alkaline remover, an organic solvent, or the like. Anoxygen plasma method can also be used as the lift-off method.

[0060] (4) Forming of Reflective Film

[0061] Next, a reflective film 6 is formed using an electrical method,with the above described patterned transparent conductive film 3 as anelectrode.

[0062] To be specific, there is an electrodeposition method (also calledmigration electrodeposition) whereby an electrodeposition polymer andpigment are dispersed, and electrodeposition coating is performed usinga transparent conductive film electrode. Electrodeposition coatingincludes anion electrodeposition and cation electrodeposition, but withanion electrodeposition, since the coated object is anode-polarized,there is a tendency to oxide elution of the electrode material, and thismay lead to corrosion, discoloration of the coating, destruction of theanticorrosion coating, and so forth, and therefore cationelectrodeposition is generally preferable.

[0063] The electrodeposition processing is performed by using a watersoluble cation type electrodeposition coating material, with thetransparent conductive film 3 as the cathode. Materials used as anelectrodeposition binder material are epoxy urethane, epoxy ester,acrylic urethane, and a cathode separation type vehicle with polyaminoresin partially neutralized and deflocculated with a lower organic acid,and also a plasticizer, hardener, flattening agent, rust preventive,slobbery stain preventive, ultraviolet ray absorbent, and brightener;and as pigments, a water soluble solution containing barium sulfate,talc, calcium carbonate, clay, organic pigments, inorganic pigments,titanium white, plastic beads, or glass beads.

[0064] From the standpoint of diffuse reflection characteristics, aninorganic pigment, and especially a titanium oxide material, is mostsuitable as a pigment for the diffuse reflection film.

[0065] A supporting salt (supporting electrolyte) can be added asnecessary to adjust the electrical conductivity of the aqueous medium.To be specific, suitable substances are sulfates which are generally andwidely used as supporting salts (salts of lithium, potassium, sodium,rubidium, aluminum, etc.), acetates (salts of lithium, potassium,sodium, rubidium, beryllium, magnesium, calcium, strontium, barium,aluminum, etc.), halide salts (salts of lithium, potassium, sodium,rubidium, calcium, magnesium, aluminum, etc.), and water soluble oxidesalts (salts of lithium, potassium, sodium, rubidium, calcium,magnesium, aluminum, etc.), of which specific examples include LiBr,KCl, Li₂SO₄, and (NH₄)₃BF₄.

[0066] In this embodiment, the transparent sheet 1 a bearing thepatterned transparent conductive film 3 is immersed in the abovedescribed electrodeposition solution, and electrodeposition is performedby passing a current to the above described transparent conductive film3 electrode. The electrodeposition conditions can be selected asappropriate, according to the type, specifications, and so forth, of thereflective film concerned, but usual conditions are an applied voltageof 20 to 400 V at a temperature of 25 to 30° C. At the time of forming areflective film 6 to a thickness of 20 to 25 μm, film forming iscompleted in approximately 2 to 3 minutes. In this embodiment, areflective film 6 thickness of 1 to 30 μm is suitable.

[0067] Another reflective film forming method, other than that describedabove, is the micell electrolysis method. This is an electrolytic methodwhereby a surface active agent mixed with a micellization agent, and apigment or dye, are dispersed in an aqueous solution, and electrolysisis performed using the transparent conductive film 3. That is, thetransparent sheet 1 a on which the transparent conductive film 3 hasbeen formed is immersed in a dispersant or micell solution obtained bydispersing or solubilizing a hydrophobic substance in an aqueous mediumusing a surface active agent, a current is passed to the above describedtransparent conductive film 3 electrode, and a reflective film 6composed of a hydrophobic substance is formed upon this conductive film3.

[0068] Materials that can be used with this method comprise variouskinds of hydrophobic substances, divided into organic substances andinorganic substances.

[0069] Hydrophobic organic substances include, for example, organicpigments, organic fluorescent materials, organic luminescent materials,and organic photosensitive materials. It is also possible to use a waterinsoluble polymer, for example general-purpose polymers such aspolycarbonate, polystyrene, polypropylene, polyamide, polyphenylenesulfide (PPS), polyphenylene oxide (PPO), and polyacrylonitrile (PAN),and also various kinds of polymers (polyvinyl pyridine etc.) such aspolyphenylene, polypyrrole, polyaniline, polythiophene, acetylcellulose, polyvinyl acetate, and polyvinylbutyral, or copolymers (suchas a copolymer of methyl methacrylate and methacrylic acid).

[0070] On the other hand, substances that can be used as hydrophobicinorganic substances include inorganic substances in which particlesurfaces have been treated to make them hydrophobic, such as titaniumoxide, titania, stannic oxide, etc., or inorganic pigment, inorganicphosphors, and so forth.

[0071] Although there are no particular restrictions relating to theshape, size, and so forth, of hydrophobic organic substances orinorganic substances, a powder with a particle diameter not exceeding 10μm is preferable.

[0072] With the micell electrolysis method, various kinds of medium,including water, a mixture of water and alcohol, or a mixture of waterand acetone, can be employed as the aqueous medium used for thin filmformation. The surface active agent used with this method can be anordinary surface active agent, but should preferably be made from aferrocene derivative. Here, ferrocene derivatives include ammonium type,ether type, and ester type derivatives.

[0073] In the micell electrolysis method, the above described surfaceactive agent and a hydrophobic organic substance or inorganic substanceare first put into an aqueous medium, and are thoroughly mixed by usinga mechanical homogenizer, ultrasonic homogenizer, pearl mill, sand mill,stirrer, high-pressure homogenizer, or the like. In this operation, thehydrophobic substance is uniformly dispersed or solubilized in theaqueous medium through the action of the surface active agent, andbecomes a diffuse liquid or micell solution. There are no particularrestrictions on the concentration of the surface active agent at thistime, but normally a surface active agent, such as the above describedferrocene derivative, that has a higher concentration than the thresholdmicell concentration, and preferably in the range from 10 μm to 0.1 M,is selected.

[0074] A supporting salt (supporting electrolyte) can be added asnecessary to adjust the electrical conductivity of the aqueous medium.

[0075] In this embodiment, the patterned transparent conductive film 3is made the electrode, and the transparent sheet 1 a including this isimmersed in a diffuse liquid or micell solution prepared in this way,and electrolysis is performed by passing a current to the abovedescribed electrode. The electrolysis conditions at this time can beselected as appropriate, according to the purpose, but usual conditionsare a liquid temperature of 0 to 70° C., and preferably 20 to 30° C., avoltage of 0.03 to 1.5 V, and preferably 0.1 to 0.5 V, and a currentdensity of not more than 10 mA/cm², and preferably 50 to 300 μA/cm².

[0076] A protective film can also be formed by using a flattening agent,as necessary, for the thin film of hydrophobic substance formed on thetransparent conductive film 3 in this way. The method is as follows.First of all, the transparent sheet 1 a on which the thin film has beenformed is mounted on a spin coater, and a flattening agent is thinly andevenly applied using a dispenser. A protective film can then be formedon the thin film by carrying out baking treatment for the prescribedtime at the prescribed temperature to harden the flattening agent.

[0077] By means of the above described electrodeposition coating ormicell electrolysis method, a reflective film 6 is formed only on theareas on which the transparent conductive film 3 has been formed, andareas with no transparent conductive film 3 become areas through whichlight passes.

[0078] The above described processes produce an optical functionalitysheet 12. Of the light entering from the side on which the reflectivefilm 6 has been formed, light incident upon areas on which thereflective film 6 is not formed, in the vicinity of the central axes ofthe microlenses, passes through the transparent sheet 1 a and reachesthe microlenses 2, and is then converted to nearly parallel light bythese microlenses 2, and emitted.

[0079] As described later, when the optical functionality sheet 12 ofthis embodiment is applied to a backlight for a liquid crystal display,light incident upon the reflective film 6 from the backlight isreflected there, returns to the backlight side, is reflected by thereflective plate of the backlight, etc., and again becomes lightincident upon the optical functionality sheet. Through repetition ofthis process, the majority of the light emitted from the backlightultimately becomes light incident upon areas on which reflective film 6is not formed, enabling outgoing light to be obtained efficiently fromthe microlenses 2.

[0080] Next, the construction and manufacturing process of an opticalfunctionality sheet that constitutes a second embodiment will bedescribed using FIG. 2.

[0081] (1) Microlens Forming

[0082] Using an Ni stamper (not shown) that has the shape of themicrolenses, a microlens sheet 1 b is formed by direct deformation of aplastic sheet, for example. The well-known hot rolling formation methodis used as the lens forming method here. The obtained microlens sheet 1b is similar to the sheet integrating microlenses 2 and a transparentsheet 1 a described in the first embodiment.

[0083] (2) Forming of Transparent Conductive Film

[0084] Using the method described in the first embodiment—that is, ITOsputtering—a transparent conductive film 3 is formed upon a transparentsheet 1 c.

[0085] Next, the transparent sheet 1 c on which this transparentconductive film 3 is formed and the microlens sheet 1 b on which themicrolenses 2 are formed are joined together with the respective formedsurfaces outward. This joining can be accomplished by using a commonlyused adhesive, or by using a method such as thermal fusion or laminationof the sheets.

[0086] (3) Patterning of Transparent Conductive Film

[0087] A positive-type resist film 27 is formed upon the transparentconductive film 3 by means of the usual well-known method, andpatterning of the transparent conductive film 3 is performed by usingthe method shown in the first embodiment.

[0088] (4) Forming of Reflective Film

[0089] A reflective film 6 is formed by using the method described inthe first embodiment—that is, electrodeposition coating with titaniumoxide as the pigment. This reflective film 6 is a white diffusereflection film containing titanium oxide, with a high reflectance ratioof at least 94% in the 400 to 700 nm wavelength range.

[0090] The above described processes produce an optical functionalitysheet 12. Since formation of the microlenses 2 and formation of thetransparent conductive film 3 can be performed by means of separateprocesses, this embodiment offers the advantage of enabling thetransparent conductive film 3 to be formed without causing unnecessarydamage through processing to the microlenses 2.

[0091] When the optical functionality sheet 12 of this embodiment isapplied to a backlight for a liquid crystal display, light incident uponthe reflective film 6 from the backlight is reflected there, returns tothe backlight side, is reflected by the reflective plate of thebacklight, etc., and again becomes light incident upon the opticalfunctionality sheet. Through repetition of this process, the majority ofthe light emitted from the backlight ultimately becomes light incidentupon areas on which reflective film 6 is not formed, enabling outgoinglight to be obtained efficiently from the microlenses 2.

[0092] Next, a third embodiment will be described by using FIG. 3.

[0093]FIG. 3 shows the construction and manufacturing process of anoptical functionality sheet that constitutes the third embodiment of thepresent invention. The details of (1) Microlens forming and (2) Formingof transparent conductive film, are the same as in the methods describedin the second embodiment, and are therefore omitted.

[0094] (3) Patterning of Transparent Conductive Film

[0095] A negative-type resist film 27 is applied upon the transparentconductive film 3 so as to produce chemical bridging of parts notirradiated with light. In this embodiment, a material of especially hightransparency is used as the photo-resist film 27.

[0096] Next, parallel light rays 28 are irradiated from the side onwhich the microlenses 2 are formed, and the photo-resist film 27 isexposed only where the parallel light rays converge. The transparentsheet 1 b, including the photo-resist film 27, is then immersed indeveloper, and the photo-resist film 27 is developed. Through thisprocessing, a resist film pattern 27 a is obtained in which the resistfilm 27 has been removed except in the vicinity of the focal points ofthe microlenses 2. Post-baking of the resist film pattern 27 a may alsobe performed as necessary.

[0097] (4) Forming of Reflective Film

[0098] A diffuse reflection film 6 is formed by using the micellelectrolysis method described in the first embodiment, in which a micellelectrolyte with titania admixed is used as a hydrophobic inorganicsubstance.

[0099] In this embodiment, the above described diffuse reflection film 6is formed on areas of the transparent conductive film 3 on which none ofthe negative-type photo-resist pattern 27 a remains. The negative-typephoto-resist pattern 27 a can then be removed, as necessary, after thediffuse reflection film 6 has been formed.

[0100] The above described processes produce an optical functionalitysheet 12. By placing this optical functionality sheet 12 so that thesurface on which the reflective film 6 has been formed faces thelight-emitting surface side of the backlight, and the surface on whichthe microlenses 2 have been formed faces the liquid crystal displayelement side, as shown in FIG. 3, the majority of the light emitted fromthe backlight becomes light incident upon areas on which reflective film6 is not formed, enabling outgoing light to be obtained efficiently fromthe microlenses 2.

[0101] Next, a fourth embodiment will be described by using FIGS. 4A-4E.

[0102] The optical functionality sheet 12 construction method conformsto the method described in the first through third embodiments.

[0103]FIG. 4A shows a structure in which a transparent sheet 1 aincluding microlenses 2 created by means of the method shown in thefirst embodiment, and a transparent sheet 1 c on which a transparentconductive film 3 has been formed, are joined together.

[0104] In FIG. 4B, with the transparent conductive film 3 as anelectrode, a metal film 29, formed thereupon using an electrical method,is used for the reflective film 6. A metal with a high reflectance ratiofor light, such as Al, Ni, or Ag, is used for this metal film 29, whichis formed by means of the well-known metal plating method.

[0105] By using a metal film 29 with an extremely high reflectanceratio, as described above, reflected light from the liquid crystaldisplay elements positioned opposite is reflected by the metal film 29,and that light can be returned again to the liquid crystal displayelement side, with the end result that the usage efficiency of the lightfrom the backlight is improved, and consequently, high brightness of theliquid crystal display apparatus is achieved.

[0106] Especially in a liquid crystal display apparatus with aconfiguration whereby a selective-polarization reflective sheet isfitted between the optical functionality sheet 12 and the liquid crystaldisplay elements, the brightness improving effect of the above describedselective-polarization reflective sheet is magnified, and increasedbrightness of the liquid crystal display apparatus is facilitated.

[0107]FIG. 4C shows sequential lamination of the patterned transparentconductive film 3, metal film 29, and white diffuse reflection film 6 onthe transparent sheet 1 c. Each film is formed by an electrical method,with the transparent conductive film as an electrode.

[0108] Using the above described configuration enables reflected lightthat is reflected back from the liquid crystal display elements to bereflected by the metal film 29 and returned again to the liquid crystaldisplay element side, and incident light from the photoconductive plateto be reflected by the white diffuse reflection film 6 and returned tothe backlight side. By this means, a higher order of brightness isrealized than when this embodiment is not used.

[0109] The sheet in FIG. 4D is created by using the method described inthe third embodiment. That is, a negative-type photo-resist 27 is firstpatterned, then a reflective film 6 is applied by electrodepositioncoating, and the negative-type photo-resist 27 is then removed tocomplete the process.

[0110]FIG. 4E shows an optical functionality sheet 12 in which areflective film 6 including a transparent conductive film 3 is processedinto trapezoid shapes by an electrodeposition coating technique. Use ofthese shapes enables the light emitted from the backlight to be inputefficiently to the microlenses 2.

[0111] When the optical functionality sheet 12 of this embodiment isapplied to a backlight for a liquid crystal display, light incident uponthe reflective film 6 from the backlight is reflected there, returns tothe backlight side, is reflected by the reflective plate of thebacklight, etc., and again becomes light incident upon the opticalfunctionality sheet. Through repetition of this process, the majority ofthe light emitted from the backlight ultimately becomes light incidentupon areas on which reflective film 6 is not formed, enabling outgoinglight to be obtained efficiently from the microlenses 2.

[0112] Next, a fifth embodiment will be described using FIG. 5. Theoptical functionality sheet shown in this embodiment has as itsobjective enlargement of the angle of visibility. The construction andmanufacturing process of this sheet will be described below.

[0113] (1) Microlens Forming

[0114] A light-diffusing layer 8 is formed on one surface of atransparent sheet 1 a by means of light diffusion processing (aprocessing method that forms randomly shaped irregularities), andmicrolenses 2 are formed on the other surface of this transparent sheet1 a (commonly called PET film, with a typical thickness of 80 μm). Themethod of forming the microlenses 2 is to inject ultraviolet-settingresin, for example, between the lens grooves of an Ni stamper that hasthe shape of the microlenses (not shown) and the transparent sheet 1 a,and harden this by irradiation with ultraviolet light.

[0115] (2) Forming of Transparent Conductive Film

[0116] A transparent conductive film 3 is formed upon thelight-diffusing layer 8 using the method described in the firstembodiment. A stannic oxide film (SnO₂) is used as the material of thetransparent conductive film.

[0117] (3) Patterning of transparent conductive film

[0118] The method shown in the first embodiment is used for patterningof the transparent conductive film using a positive-type resist film.The details are omitted here.

[0119] (4) Forming of Light-Blocking Film

[0120] Using the method described in the first embodiment, alight-blocking film 7 is formed on the parts on which the transparentconductive film 3 has been formed. An electrodeposition coating materialwith black pigment admixed is used for the electrodeposition coating forforming the light-blocking film 7.

[0121] By this means, an optical functionality sheet 18 enabling theangle of visibility to be enlarged (referred to as “angle of visibilityenlargement sheet” below) is created.

[0122] As will be described later, when, for example, the microlensformation surface of the angle of visibility enlargement sheet 18 ispositioned on the liquid crystal display element side so that thesurface on which the light-blocking layer is formed is toward theviewer, light passing through the liquid crystal display elements isconverged by the microlenses 2, then diffused by the light-diffusinglayer 8, and is emitted from the aperture areas (areas where alight-blocking layer 7 has not been formed) in the vicinity of thecentral axes of the microlenses 2. At this time, the outgoing light hasan angle of divergence in accordance with the NA of the microlenses 2and the characteristics of the light-blocking layer 7, and as a result,it is possible to obtain a liquid crystal display image exhibitingcharacteristics of a wider angle of visibility and higher contrast thanwhen this embodiment is not used.

[0123] Next, another embodiment of an angle of visibility enlargementsheet will be described, as a sixth embodiment, using FIG. 6

[0124] (1) Microlens Forming

[0125] A plastic sheet (for example polycarbonate film, with a thicknessof approximately 50 μm) is deformed directly, using an Ni stamper onwhich microlens shapes are formed, and a transparent sheet 1 b bearingmicrolenses 2 is created. The well-known hot rolling formation method isused as the microlens 2 forming method.

[0126] The microlens sheet obtained by the above described process is anintegral entity combining the microlenses 2 and transparent sheet 1 b.

[0127] (2) Forming of Transparent Conductive Film

[0128] By using the method described in the first embodiment, atransparent conductive film 3 is formed upon the surface of thetransparent sheet 1 b on which the microlenses 2 have not been formed.

[0129] (3) Patterning of Transparent Conductive Film

[0130] The method shown in the first embodiment is used for patterningof the transparent conductive film 3 using a positive-type resist. Thatis, a resist pattern 27 a is formed by performing self-alignmentexposure using parallel ultraviolet light rays 28 through the use of themicrolenses 2, and development processing. Etching is then performed onthe transparent conductive film 3, and the transparent conductive film 3is patterned.

[0131] (4) Forming of Light-Blocking Film

[0132] Forming of the light-blocking film 7 is performed by using themethod described in the first embodiment. That is, an electrodepositioncoating technique is used, and an electrodeposition coating materialwith black pigment admixed is used for the electrodeposition coating forforming the light-blocking film.

[0133] By means of the above method, an angle of visibility enlargementsheet 18 can be obtained.

[0134] The effect obtained when the above described angle of visibilityenlargement sheet 18 is used is similar to the case of the fifthembodiment, and when, for example, the microlens formation surface ofthe angle of visibility enlargement sheet 18 is positioned on the liquidcrystal display element side so that the surface on which thelight-blocking layer is formed is toward the viewer, light passingthrough the liquid crystal display elements is converged by themicrolenses 2, then diffused by the light-diffusing layer 8, and isemitted from the aperture areas (areas where a light-blocking layer 7has not been formed) in the vicinity of the central axes of themicrolenses 2.

[0135] At this time, the outgoing light has an angle of divergence inaccordance with the NA of the microlenses 2 and the characteristics ofthe light-blocking layer 7, and as a result, it is possible to obtain aliquid crystal display image exhibiting characteristics of a wider angleof visibility and higher contrast than when this embodiment is not used.

[0136] Next, another embodiment of an angle of visibility enlargementsheet will be described, using FIG. 7

[0137] (1) Microlens Forming

[0138] A TAC film (thickness: 30 μm), for example, is used as atransparent sheet 1 b, and microlenses 2 are formed on its surface. Thewell-known hot pressing method, using an Ni stamper (not shown) on whichmicrolens shapes are formed, is used as the microlens forming method.

[0139] (2) Forming of Transparent Conductive Film

[0140] The method described in the first embodiment is used for formingof the transparent conductive film in this embodiment.

[0141] (3) Patterning of Transparent Conductive Film

[0142] Patterning is performed by means of the method described in thethird embodiment, using a highly-transparent negative-type resist thatcontains a light-diffusing substance (for example a substance withplastic or glass beads admixed). By means of self-alignment exposure anddevelopment, a negative-type resist pattern 27 a with a light diffusingfunction is formed.

[0143] (4) Forming of Light-Blocking Film

[0144] By using the method described in the first embodiment, alight-blocking layer 7 is formed upon the areas of the transparentconductive film 3 where the negative-type resist pattern 27 a has beenformed. In this embodiment, micell electrolysis is used, and a coatingmaterial with a black pigment admixed is used as the micell electrolyticcoating material for forming the light-blocking film.

[0145] By means of the above described method, an angle of visibilityenlargement sheet 18 can be obtained. Due to the synergy of themicrolenses 2 and the light-diffusing layer 8, this sheet 18 exhibits agreater angle of visibility enlargement effect than when this embodimentis not used. As will be described later, when the angle of visibilityenlargement sheet 18 of this embodiment is applied to the screen of arear-projection type liquid crystal projector, for example, an imagewith a wide angle of visibility and high contrast can be obtained on alarge screen.

[0146] Next, another embodiment of an angle of visibility enlargementsheet will be described, using FIG. 8.

[0147] (1) Microlens Forming

[0148] A polycarbonate film, for example, is used as a transparent sheet1 b, and microlenses 2 are formed on its surface. The well-known hotpressing method, using an Ni stamper (not shown) on which microlensshapes are formed, is used as the microlens forming method.

[0149] Next, ultraviolet-setting resin containing plastic beads, forexample, is applied to the surface on which microlenses 2 have not beenformed, then the above described resin is hardened by irradiation withultraviolet light, and a light-diffusing layer 8 is formed.

[0150] (2) Forming of Transparent Conductive Film

[0151] A transparent conductive film 3 is formed upon thelight-diffusing layer 8, using the method described in the firstembodiment.

[0152] (3) Patterning of Transparent Conductive Film

[0153] The transparent conductive film 3 is patterned by means of themethod described in the first embodiment, using a positive-type resistfilm. That is, a resist pattern 27 a is obtained by performingself-alignment exposure using parallel ultraviolet light rays 28 throughthe use of the microlenses 2, and development processing. Thetransparent conductive film 3 is then patterned using the well-known wetetching method.

[0154] (4) Forming of Light-Blocking Film

[0155] By using the method described in the first embodiment, alight-blocking layer 7 is formed on areas where the transparentconductive film 3 has been formed. In this embodiment, micellelectrolysis is used, and a coating material with a black pigmentadmixed is used as the micell electrolytic coating material for formingthe light-blocking film.

[0156] By means of the above described method, an angle of visibilityenlargement sheet 18 can be obtained. Due to the synergy of themicrolenses 2 and the light-diffusing layer 8, this sheet 18 exhibits agreater angle of visibility enlargement effect than when this embodimentis not used. As will be described later, when the angle of visibilityenlargement sheet 18 of this embodiment is applied to the screen of arear-projection type liquid crystal projector, for example, an imagewith a wide angle of visibility and high contrast can be obtained on alarge screen.

[0157] Various kinds of processing can be performed for the opticalfunctionality sheet described above, such as reflection prevention orelectrostatic charge prevention on the surface of the microlenses 2 orthe upper surface on which the reflective film 6 and light-blocking film7 are formed, or hard-coat film or adhesive layer applicationprocessing, according to its use and required characteristics. Inaddition, the sheet can also be used bonded to another base material(such as a plastic or glass substrate, for example).

[0158] Now, with the above described optical functionality sheet in thefirst through fourth embodiments, when light with various directions oftravel entering from the surface on which the microlens group is formedpasses through the above described optical sheet, and is emitted to theother surface on which a reflective film composed of a transparentconductive film and white diffuse reflection film is formed, the opticalfunctionality sheet can give directivity to the outgoing light, emittingnearly parallel light, for example, and at least, areas in the vicinityof the focal points of light entering from the microlens group side aremade apertures.

[0159] An embodiment (planar light source) in which the above describedoptical functionality sheet is applied to a backlight for a TFT-LCD,which is one of its typical uses, will be described below.

[0160] The backlight referred to here is a light source for shininglight uniformly onto a TFT-LCD from the rear. There is an edge-lighttype and a directly-beneath type, according to the location of the lightsource with respect to the display surface of the TFT-LCD.

[0161] With the edge-light type backlight shown in FIG. 9, basicallycold cathode tubes 9, which are line light sources, are installed at thesides of a photoconductive plate 10 of excellent transparency installedopposite the display surface of a TFT-LCD (not shown), light from thecold cathode tubes 9 is scattered using dots 11 provided on the bottomsurface of this photoconductive plate 10, and light is emitted towardthe display surface of the TFT-LCD (the top of the page in FIG. 9).

[0162] With the optical functionality sheet 12, an edge-light type ordirectly-beneath type backlight need not be specially modified; it ispossible for light that has directivity to be emitted to the TFT-LCD byplacing the sheet opposite the light emitting surface of thebacklight—that is, the photoconductive plate 10.

[0163] Next, the function and effect will be described for the casewhere the above described optical functionality sheet 12 is mounted onan edge-light type of upper-surface-scatter type backlight, as shown inFIG. 9.

[0164] Of the light 13 that is repeatedly reflected inside thephotoconductive plate 10, light is emitted externally at various anglesas light 13 a from the emitting surface (the surface on which dots 11are not formed) of the photoconductive plate 10.

[0165] Then, since the transparent conductive film 3 and reflective film6 formed on the optical functionality sheet 12 are located opposite thissurface, the light 13 a incident upon this reflective film 6 isreflected by that reflective film 6 and returned to the photoconductiveplate 10 again.

[0166] This light again follows the above described path, and the finalresult is that loss is kept to a minimum for the light emitted from thecold cathode tubes 9. Also, the light 13 emitted toward the bottom ofthe photoconductive plate 10 is reflected by a reflective sheet 31, andreturns again to the photoconductive plate 10.

[0167] On the other hand, the transparent conductive film 3 andreflective film 6 have apertures 15 in the vicinity of the focal pointsof the microlenses 2, or in the vicinity of the central axes of themicrolenses 2, and light 16 incident upon these apertures 15 isrefracted by the microlenses 2, and becomes light 17 that hasdirectivity—that is, nearly parallel light—and is emitted toward thedisplay surface of the TFT-LCD (not shown).

[0168] By changing the shape of the apertures 15 and microlenses 2, thethickness of the transparent sheet 1 a used for lens forming, and so on,as appropriate, it is possible to optimize the degree of lightdirectivity, its direction, and so forth, according to the intendedapplication or use.

[0169] It is also possible to place a plurality of diffusion sheets,prism sheets, or the like, between the photoconductive plate 10 and theoptical functionality sheet 12, for the purpose of further optimizingthe directivity of the light 13 emitted from the cold cathode tubes 9.

[0170] The purpose of the above described optical functionality sheet inthe fifth through eighth embodiments is to enlarge the angle ofvisibility of light emitted from the display unit of a TFT-LCD (notshown), and a embodiment in which it is applied to enlarging the angleof visibility of a TFT-LCD, which is a typical use, will now bedescribed using FIG. 10.

[0171] The surface of an optical functionality sheet 18 on whichmicrolenses 2 are formed is located opposite the display surface side ofa TFT-LCD, and nearly parallel image light 19 emitted from the displaysurface of the TFT-LCD is converged at transparent areas 5 by themicrolenses 2, is then diffused by a light-diffusing layer 8, and thenstrikes a transparent sheet 1 c.

[0172] The image light 19 incident upon the transparent sheet 1 c isrefracted at the boundary between the air and the transparent sheet 1 c,and is emitted externally. Since, at this time, the image light 19 isconverged by the microlenses 2 before being emitted, it becomesdivergent image light 20 that has an angle of divergence in accordancewith the NA of the microlenses 2 and the characteristics of thelight-diffusing layer 8. It is thus possible to obtain image light 20with a wide angle of visibility.

[0173] On the other hand, the influence of detrimental external light onthe visibility of the image, which is one factor in TFT-LCD displayquality, can be suppressed by forming a light-blocking film 7constituting a component of the angle of visibility enlargement sheet18, using a black light absorber, and as a result, it is possible todisplay TFT-LCD images with improved contrast.

[0174] Next, a embodiment in which the above described opticalfunctionality sheet is applied to a liquid crystal display apparatuswill be described, by using FIG. 11.

[0175] The liquid crystal display apparatus shown in FIG. 11 comprises abacklight unit 4, a first optical functionality sheet 12, a secondoptical functionality sheet 18, and a liquid crystal display panel 21.In the first optical functionality sheet 12, first microlenses 2 areformed on one surface of a first transparent member 1 a, and areflective member 6 is formed on the other surface, in areas other thanthe vicinity of the central axes of the first microlenses 2.

[0176] In the second optical functionality sheet 18, second microlenses2 are formed on one surface of a second transparent member 1 b, and alight-blocking member 7 is formed on the other surface, in areas otherthan the vicinity of the central axes of the second microlenses 2.

[0177] The first microlenses 2 and second microlenses 2 face therespective surfaces of the liquid crystal display panel 21, and thereflective member 7 is located so as to face the light emitting side ofthe backlight unit 4.

[0178] Light emitted from the backlight unit 4 is converted tocollimated light by the first optical functionality sheet 12, and passesthrough the liquid crystal display panel 21, becoming image light 19.

[0179] This image light 19 strikes the second optical functionalitysheet 18, is converged by the second microlenses 2, and then becomesdiffused light and forms divergent image light 20.

[0180] In this way, it is possible to display light from the backlightunit 4 as image light that has a prescribed angle of visibility, at highbrightness, and with a high contrast ratio.

[0181] It is also possible, as necessary, to place a film 30 (such asDBEF manufactured by 3M Corporation, or PCF manufactured by Nitto DenkoCorporation) that has a selective-polarization reflection function, forexample, between the first optical functionality sheet 12 and the liquidcrystal display panel 21, as shown in FIG. 11, to further improve thebrightness.

[0182] The microlenses 2 formed on the first and second opticalfunctionality sheets 12 and 18 shown this embodiment should preferablybe smaller than the pixels 22 of the liquid crystal display panel 21(common pixel dimensions are about 90×270 μm).

[0183] Also, the optical functionality sheets illustrated in FIG. 11both have microlenses 2 and a reflective film 6 or light-blocking film 7as component elements, but one or the other can also be created by amethod other than that in this embodiment, as necessary. Also, even ifthe first and second microlenses 2 are given the same shape, theirfunctions do not change, and this makes it possible to use a common dieor stamper for microlens forming.

[0184] Another embodiment in which the above described opticalfunctionality sheet is applied to a liquid crystal display apparatuswill now be described, using FIGS. 12A and 12B.

[0185] The liquid crystal display apparatus shown in FIG. 12A comprisesa light source 24, a liquid crystal display panel 21, mirrors 25, ascreen 26, and an optical functionality sheet 18. In the opticalfunctionality sheet 18, microlenses 2 are formed on one surface of atransparent member, and a light-blocking member 7 is formed on the othersurface, in areas other than the vicinity of the central axes of themicrolenses 2, and the microlenses 2 of this optical functionality sheet18 face the light emitting surface of the screen 26.

[0186] Light emitted from the light source 24 passes through the liquidcrystal display panel 21 and is projected onto the screen 26 via themirrors 25. Light projected onto the screen 26 is emitted externally viathe microlenses 2, light-blocking film 7, and light-diffusing layer 8 ofthe optical functionality sheet 18.

[0187] By means of separately provided driving means (not shown), thelight source 24, liquid crystal display panel 21, etc., are controlled,image information displayed on the liquid crystal display panel 21 isreflected using the mirrors 25, and that image information is projectedin enlarged form on the screen 26.

[0188] By using a rear-projection type image display apparatus with theabove described configuration, it is possible to obtain an image withbetter angle of visibility characteristics and contrast characteristicsthan when an optical functionality sheet 18 is not mounted on the screen26.

[0189] By forming microlenses and a reflective film or light-blockingfilm, respectively, on the two sides of a transparent sheet, asdescribed above, it is possible to realize with high precision anoptical functionality sheet with excellent directivity with respect toincident light, and excellent angle of visibility characteristics.

[0190] Moreover, by using the above described optical functionalitysheet, it is possible to realize a planar light source with excellentdirectivity, and also an image display apparatus with excellent displayquality that has characteristics of a wide angle of visibility and highcontrast.

[0191] While we have shown and described several embodiments inaccordance with our invention, it should be understood that disclosedembodiments are susceptible of changes and modifications withoutdeparting from the scope of the invention. Therefore, we do not intendto be bound be the details shown and described herein but intend tocover all such changes and modifications as fall within the ambit of theappended claims.

What is claimed is:
 1. An optical functionality sheet, comprising: atransparent member that has microlenses on one surface; and a reflectivemember; wherein said reflective member is configured by at least atransparent conductive film and a white diffuse reflection film, and isprovided on the other surface of said transparent member, in areas otherthan the vicinity of the central axes of said microlenses; and of thelight entering from said reflective member side, light emitted via saidmicrolenses is converted to nearly parallel light.
 2. An opticalfunctionality sheet, comprising: a first transparent member that hasmicrolenses; and a second transparent member that has a reflectivemember, wherein said first transparent member and said secondtransparent member are joined together at the surfaces that do not havemicrolenses or a reflective member; said reflective member is configuredby at least a transparent conductive film and a white diffuse reflectionfilm, and is provided in areas other than the vicinity of the centralaxes of said microlenses; and of the light entering from said reflectivemember side, light emitted via said microlenses is converted to nearlyparallel light.
 3. An optical functionality sheet, comprising: atransparent member that has microlenses on one surface; and a reflectivemember provided on the other surface of said transparent member, whereinsaid reflective member is configured by at least a transparentconductive film and a white diffuse reflection film, and said whitediffuse reflection film is provided in areas other than the vicinity ofthe central axes of said microlenses; and of the light entering fromsaid reflective member side, light emitted via said microlenses isconverted to nearly parallel light.
 4. An optical functionality sheet,comprising: a transparent member that has microlenses on one surface;and a light-blocking member; wherein said light-blocking member isconfigured by at least a transparent conductive film and a blacklight-blocking film, and is provided in areas other than the vicinity ofthe central axes of said microlenses, on the other surface of saidtransparent member; and of the light entering from said microlens side,light emitted via said light-blocking member is converted to diffusedlight.
 5. An optical functionality sheet, comprising: a firsttransparent member that has microlenses; and a second transparent memberthat has a light-blocking member; wherein said first transparent memberand said second transparent member are joined together at the surfacesthat do not have microlenses or a reflective member; said light-blockingmember is configured by at least a transparent conductive film and ablack light-blocking film, and is provided in areas other than thevicinity of the central axes of said microlenses; and of the lightentering from said microlens side, light emitted via said light-blockingmember is converted to diffused light.
 6. An optical functionalitysheet, comprising: a transparent member that has microlenses on onesurface; and a light-diffusing layer and light-blocking member providedon the other surface of said transparent member; wherein saidlight-blocking member is configured by at least a transparent conductivefilm and a black light-blocking film, and said black light-blocking filmis provided in areas other than the vicinity of the central axes of saidmicrolenses; and of the light entering from said microlens side, lightemitted via said light-blocking member is converted to diffused light.7. The optical functionality sheet according to claim 1 , wherein saidwhite diffuse reflection film is configured by at least a first metalreflective film and a second metal reflective film.
 8. The opticalfunctionality sheet according to claim 2 , wherein said white diffusereflection film is configured by at least a first metal reflective filmand a second metal reflective film.
 9. The optical functionality sheetaccording to claim 3 , wherein said white diffuse reflection film isconfigured by at least a first metal reflective film and a second metalreflective film.
 10. The optical functionality sheet according to claim7 , wherein said first metal reflective film is a titanium oxide film.11. The optical functionality sheet according to claim 7 , wherein saidsecond metal reflective film is an aluminum film.
 12. The opticalfunctionality sheet according to claim 1 , wherein said reflectivemember comprises apertures in areas in the vicinity of the central axesof said microlenses, and said apertures are arranged so as to becomenarrower in the direction from the surface of said reflective membertoward said microlenses.
 13. The optical functionality sheet accordingto claim 2 , wherein said reflective member comprises apertures in areasin the vicinity of the central axes of said microlenses, and saidapertures are arranged so as to become narrower in the direction fromthe surface of said reflective member toward said microlenses.
 14. Anoptical functionality sheet according to claim 3 , wherein saidreflective member comprises apertures in areas in the vicinity of thecentral axes of said microlenses, and said apertures are arranged so asto become narrower in the direction from the surface of said reflectivemember toward said microlenses.
 15. The optical functionality sheetaccording to claim 6 , wherein said light-diffusing layer is provided inareas in the vicinity of the central axes of said microlenses, and atleast on the upper or lower surface of said transparent conductive film.16. A planar light source, comprising: a backlight unit; and an opticalfunctionality sheet; wherein in said optical functionality sheet,microlenses are provided on one surface of a transparent member, and areflective member is provided on the other surface of said transparentmember, in areas other than the vicinity of the central axes of saidmicrolenses; and said reflective member is located so as to face thelight emitting side of said backlight unit.
 17. A liquid crystal displayapparatus, comprising: a backlight unit; a first optical functionalitysheet; a second optical functionality sheet; and a liquid crystaldisplay panel; wherein in said first optical functionality sheet, firstmicrolenses are provided on one surface of a first transparent member,and a reflective member is provided on the other surface of said firsttransparent member, in areas other than the vicinity of the central axesof said first microlenses; in said second optical functionality sheet,second microlenses are provided on one surface of a second transparentmember, and a light-blocking member is provided on the other surface ofsaid second transparent member, in areas other than the vicinity of thecentral axes of said second microlenses; said first microlenses and saidsecond microlenses face the respective surfaces of said liquid crystaldisplay panel; and said reflective member is located so as to face thelight emitting side of said backlight unit.
 18. A liquid crystal displayapparatus, comprising: a light source; a liquid crystal display panel;mirrors; a screen; and an optical functionality sheet; wherein in saidoptical functionality sheet, microlenses are provided on one surface ofa transparent member, and a light-blocking member is provided on theother surface of said transparent member, in areas other than thevicinity of the central axes of said microlenses, and said microlensesface the light emitting surface of said screen.